While the United States and Russia possess more than 90 percent of the world’s nuclear weapons, the fact that seven other nations have nuclear weapons, albeit in smaller quantities, is highly significant.

The report “Nuclear Famine: Two Billion People at Risk?” by Ira Helfand warns that even “a limited, regional nuclear war between India and Pakistan would cause significant climate disruption worldwide.” The resulting global cooling would significantly affect “agriculture, food supplies, and human nutrition” and could result in billions of deaths.

Even North Korea’s handful of nuclear weapons is dangerously destabilizing [“Former U.S. officials plan talks with N. Koreans,” front page, Feb. 20]. The Bulletin of Atomic Scientists’ Doomsday Clock is at two and a half minutes to midnight, due in large part to President Trump’s provocative statements. It’s high time to take President John F. Kennedy’s 1961 warning to heart: “The weapons of war must be abolished before they abolish us.”